Sandwich drafting board structure



June 25, 1968 H. w. GRAY ET AL 3,3 9,

SANDWICH DRAFTING BOARD STRUCTURE Filed April 6, 1966 United StatesPatent SANDWICH DRAFTING BOARD STRUCURE Harold W. Gray, Toronto,Ontario, and Arthur L. W.

Watt, Willowdale, Ontario, Canada, assignors to The Hughes-Owens CompanyLimited, Montreal, Quebec,

Canada Filed Apr. 6, 1966, Ser. No. 540,628 3 Claims. (Cl. 52-309)ABSTRACT OF THE DISCLOSURE The invention comprises a drafting boardhaving a core formed of expanded plastic composition foam, a rigid coversheet is applied to each major side surface of the foam core and, on oneside of the board a sheet of resilient material, such as linoleum, isfixed to constitute the drafting surface.

This invention relates to table top structure and particularly todrafting board structures which avoid the difficiencies of wooden boardsand at the same time yield the requisite lightness and dimensionalstability.

Conventional wooden drafting boards are known to be relatively expensiveand inherently subject to warpage and swelling upon alternate exposureto moist and dry arr.

Accordingly it is an object of this invention to provide a light andrigid table top, particularly suitable for use as a drafting board,which maintains its original flatness and dimensional stabilityregardless of the conditions of air in which it is used.

We have found that it is possible to devise such a stable boardstructure through the use of a layer of relatively stiff foamy materialsandwiched between two sheets of rigid material. Preferably, we providea frame around the edges of the assembly to give it the desiredstructural rigidity, and glue the sheets to the layer of foamy material.

Summary 0 the invention The present invention resides in a draftingboard comprising a rectangular sheet of expanded plastic compositionfoam. A rectangular frame is fixed to the edges of the foam sheet and arigid sheet is applied to each major side surface of the foam sheet. Asheet of resilient material, such as linoleum, is fixed to one of therigid cover sheets in completely overlying relation to the foam sheet toconstitute a drafting surface.

In the drawings which illustrate an embodiment according to the presentinvention,

FIGURE 1 is a perspective view of a drafting board and FIGURE 2 is across section taken along line IIII in FIGURE 1.

Referring to FIGURE 1 of the drawings, reference numeral 1 indicatedgenerally a drafting table top mounted on a support 2 which includes apair of legs 3 each having a pivotal connection arrangement 4 to couplethe legs 3 to the table top 1 so as to allow angular adjustment thereofabout the longitudinal axis of the table top 1. The front edge In of thedrafting table top I is provided with a pencil rack 5. Such supports andpencil racks are well known in the art and any conventional designthereof ice may be used in connection with table top structuresaccording to the present invention.

As shown in FIGURE 2 of the drawings the structure of the present tabletop I essentially comprises a layer of low density, relatively stiff andpreferably non-permeable foamy material 6 such as expanded plastic,sandwiched between two sheets of rigid material 7, and frame members 8disposed around the assembly so as to give it more structural rigidity.The edges of the sheets 7 are secured to the rigid members 8 by anysuitable fastening means such as rivets or bolts 9, and the intermediateportion of the sheets 7 are preferably glued to the layer 6.

Channel members 10 may be disposed around the outer edges of the frame 8so as to overlie margins of the sheets 7. The channel member 10m at thefront of the table top I may be shaped so as to form the pencil rack 5.Finally, a layer 11 of firm but resilient material is applied to the topsurface of the table so as to cover the upper sheet 7 to provide a gooddrawing surface.

In a preferred embodiment the layer of foamy material 6 consists ofexpanded polystyrene plastic such as known under the trademarkStyrofoam, and the sheets 7 are made of aluminum. Frame members 8 may bea properly shaped aluminum extrusion or pieces of plywood secured to theupper and lower sheets 7.

The channel members 10, preferably aluminum, trim the outer edges of theassembly and are secured thereto by means of rivets, or wood screws whenframe 8 is made of plywood. The covering 11 of the upper surface of thedrafting board may be a layer of linoleum which is known to provide asatisfactory drawing surface.

Pieces of plywood, plastic or metal may be used to provide rigidstructural members across the board or along its length as required.

What we claim as our invention is:

1. A drafting board comprising a rectangular sheet of expanded plasticcomposition foam, a rectangular frame fixed to the edges of said sheet,a rigid sheet completely overlying and engaging each major side surfaceof said foam sheet, means securing said rigid sheets to said frame, saidmeans including channel members overlying the edges of said frame andthe marginal portions of said rigid sheets and a sheet of resilientmaterial engaging and fixed to one of said rigid sheets and completelyoverlying said foam sheet.

2. A drafting board as defined in claim 1, wherein said foam sheet is apolystyrene resin.

3. A drafting board as defined in claim 1, wherein said resilient sheetis linoleum.

References Cited UNITED STATES PATENTS 2,066,718 1/1937 Dietz 52-623 X2,612,423 9/1952 Hennell 1089O 2,664,596 1/1954 Greig 52624 X 2,911,27411/1959 Grube 52-623 X 3,147,336 9/1964 Mathews 52-615 X 3,182,7675/1965 Kuehl 52-6 27 X 3,219,383 11/1965 Nerern 52-627 X 3,235,0402/1966 Ellis 52623 3,323,797 6/1967 Horton 52-615 X DAVID J.WILLIAMOWSKY, Primary Examiner.

' D. L. TAYLOR, Assistant Examiner.

